THE ALTERNATION PROBLEM 



369 



initial choice with a high degree of perfection. Some typical 

 examples of these curves are given in figures 3 and 4. The 

 solid line 1 represents the curve of learning for the problem 

 as a whole, while the dotted curve 2 represents the course of 

 mastery of the initial choice. Fig. 4 represents the exceptional 

 case in which the solution of the two aspects of the problem 

 were related and equally difficult. In fig. 3 the initial choice 

 exhibited the greater difficulty; for some periods the two aspects 

 were mastered together, at other times progress was antagonistic, 

 while for most periods one problem was mastered independently 

 of the other. 



Tnals 170 



Trials 170 



Figure 3. — Graph 1, individual learning Figure 4. — Graph 1, individual learning 

 curve; graph 2, curve of learning for curve; graph 2, curve of learning for 

 mastery of initial choice. mastery of initial choice. 



Separate records were kept for the mastery of the two posi- 

 tion habits. A comparison of the individual graphs reveals two 

 general results. 1. Five animals found the mastery of the left 

 position to be the easier. More correct choices of the left exit 

 were consistently made for all stages of learning. The two 

 positions were practically equally difficult for the other three 

 animals. Mastery of the two habits was synchronous. 2. With 

 four animals, the two habits antagonized each other's progress 

 for the first half or two-thirds of the learning period. A rise in 

 one curve was generally correlated with a fall in the other, 



